How can Abraham & Moses dare argue with God?!

If God is the arbiter of morality, then how could it be that Avraham (S’dom) or Moshe (golden calf) could argue with God? One would think that whatever God suggests would, by definition, have to be totally moral and perfect. If Avraham and Moshe were right to argue, then where could they have gotten that sense of morality from, if not God?

Obviously God is perfect and the ultimate in morality. But part of that perfection includes His altruistically giving us the opportunity to be like Him ("imitateo dei"), and demand morality and good for the Jewish people, and fearlessly stand up for justice, even under extreme circumstances! These are written for eternity in the Torah, to teach us how much more so we must stick out our necks & dare argue with man, including powerful and frightening kings, for the sake of justice & Am Yisrael, whom our Father wants us to endlessly love and show unlimited self-sacrifice for our holy nation and ideals.